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This work successfully obtains a positive temperature coefficient of resistivity characteristics with critical temperature (Tc) at around 490 and 420 °C for PbTiO3 (PT), and (Pb0.9Sr0.1)TiO3 (PST) materials, respectively. The tetragonality of these materials are (c/a)PT=1.065 and (c/a)PST=1.046. In addition, the donor level of Y3+ ions in PT materials [(Ed)PT=0.09–0.11 eV] is smaller than that in PST materials [i.e., (Ed)PST=0.29–0.40 eV]. The resistivity jumping ratios of the two materials are similar, that is, (ρmax/ρmin)PT≅102.2 and (ρmax/ρmin)PST≅101.6. Multiple-Tc resistivity-temperature (ρ-T) characteristics are observed, that is ascribed to the formation of an incomplete core-shell microstructure with the Pb-deficient shell not entirely surrounding the stoichiometric core.

This article presents the structural properties of silicon epitaxy grown at 200–600 °C by electron-beam evaporation in an ultrahigh vacuum system. Reflection high-energy electron diffraction was used to inspect wafer surface. Cross-sectional transmission electron microscopy was used to observe the epitaxial microstructure. The impurity profiles of epitaxial layers and epitaxy/substrate interface were measured by secondary ion mass spectroscopy. Furthermore, structural characteristics of the epitaxial films grown at different process conditions were summarized to explore the key parameters that control the epitaxial quality. In addition to ex situ cleaning prior to loading, the wafer was in situ cleaned by thermal desorption in the growth chamber at 840 °C. The thickness of the silicon epitaxial layer is about 0.1 μm, which was grown at a rate of 0.020 nm/s or higher.